LP,
That very bright Guitar sound could be a combination of the following.
1/ Bridge pickup on Guitar being used.
2/ Tone control on Guitar on full.
3/ Presence Control on amp cranked up High.
4/ Bright Sounding Mic angled towards speaker cone on Amps Speaker Box.
5/ Guitar sound leaking into the drummers overhead Mics... via a monitor speaker... so the drummer can hear the guitar sound.
6/ Sound engineer adding some High end EQ to the sound.
7/ Guitar sound leaking into the Mic used for the Bass player for vocals.
8/ Guitar sound leaking into lead vocal mic.
Just a guess.
Cheers.
